Repair Split Wood Deck Supports

Learn how to repair wooden deck or porch supports that have split. Find out how to sand the posts before using wood filler when fixing deck or porch support posts.

LESLIE: Walter in Montana tunes in on KGEZ and you’ve got a porch question. What can we answer for you?

WALTER: Well, I have supports on my deck that support the roof[1] and they are four-sided and they meet at 45-degree angles. And in the five years the house was built now it’s – they’ve separated and split apart and there’s white paint showing inside. They’re split about one-eighth of an inch on the corners and I’m wondering how best to fill those and how to handle it.

TOM: So these are columns that are split?

WALTER: Yes, they are.

TOM: OK, the wood itself is split?

WALTER: No, they’re composed of four pieces …

TOM: OK.

WALTER: … and where they join it’s at 45-degree angles.

TOM: OK.

WALTER: It’s very sharp.

TOM: Alright. Well, here’s what you’re going to want to do. First of all, obviously you’re going to have to sand them all down[2] and then you’re going to use a wood filler to fill in all of those gaps. If there’s any loose pieces they need to be secured so that they’re not moving. Once they’re sanded down and the filler is applied, all of those gaps are closed, then it’s going to be real important that you use an oil-based primer[3] and seal all of the exposed surfaces of those columns. Once you’re done with the primer then you can put a finish coat on top of it which does not have to be oil-based but I would definitely recommend an oil-based primer to seal it in and it’ll give you some dimensional stability.

WALTER: Sounds good.

TOM: Terrific. Walter, thanks so much for calling us at 888-MONEY-PIT.